The present invention is directed to a valve for use in a tank for loading, unloading or sealing the tank. While this valve is useful for various type tanks, it is particularly useful in a mobile tank.
Valves especially for railroad tank cars and tank trucks must be capable of surviving accidents and collisions, and even over turning of the tank while still preventing the contents of the tank escaping through the valve. Generally, this requires a complicated valve, with protective features and consequently such valves are expensive.
The present valve can be used as a regular tank valve for loading or unloading product into the tank, or can be a backup safety unloading valve for use in an emergency. While the valve may extend out of the tank for loading and unloading, it can be manipulated to provide an internal tank valve which is generally flush with the tank and less subject to damage in the event of an accident.